Automatic shunt



w. c. NEAHR.

AUTOMATIC SHUNT.

APPLICATION FILED AUG-I4. 1917.

1,377,267, Patented May 10,1921.

COLORADO, ASSIGNOR TO THE 0F DENVER, COLORADO,

WILL G. NEAHR, DENVER,

MANUFACTURING COMPANY, COLORADO.

PROTECTIVE SIGNAL A CORPGRATION OF AUTOMATIC SHUNT.

Application filed August 14, 1917.

To aZZ whom it may concern:

Be it known that I, WILL C. NEAHR, a citizen of the United States, residing at Denver, in the" county of Denver and State of Colorado, have invented certain new and useful Improvements in Automatic Shunts, of which the following is a specification.

As is well known to those skilled in the art, where a plurality of electrically operated instruments are placed in series in a circuit, it one of'the instruments becomes inoperative by reason of the failure of current to pass therethrough so that said current is broken or materially weakened, the other instruments will either become inoperative, or in case of the weakening of the current, will be greatly reduced so far as the operative force is concerned. Thus, as an example, it is often the custom to utilize lamps in series, and in case the filament of one lamp becomes ruptured, the others are of course extinguished.

The primary object of the present invention is to provide simple and practical means whereby it a lamp or other instrument in series becomes inoperative a shunt circuit will be automatically created across the same, so that the other lamps or instruments 7 will not be permanently affected.

A further and important object is to so construct this shunt creating means that when the instrument is in normal operation, practically no current is lost by reason of said shunt producing mechanism. r

A further and important object is to provide a structure that is relatively simple and exceedingly compact, so that it will occupy but little space and may be utilized in connection with the ordinary standard plug and socket devices in general use.

One embodiment of the invention is illustrated in the accompanying drawings, wherein:

Figure 1 is a view in elevation showing a set of lamps in series, with one of the devices in place.

Fig. 2 is a vertical sectional view throughsuch device.

Fig. 3 is a view in section at right angles to Fig. 2.

Fig. 4 is a bottom plan view.

Fig. 5 is a diagrammatic view illustrating the various circuits established.

Similar reference numerals designate cor- Speci'fioation of Letters Patent.

Patented May 11 0 1221.

Serial No. 186,215.

responding parts in all the figures of the drawings.

In the embodiment disclosed, a metallic shell 6 is employed, one end of which is formed'into a plug member 7 that is exteriorly threaded, as shown. The other end forms an internally threaded socket member 9. The inner end of the socket member is defined by an insulator block or plate .10 suitably secured within the shell and carrying a central contact element 11 that con stitutes the usual contact element of a socket member. The plug 7 is likewise provided on its end with a contact element 12 insulated therefrom, as shown at 13. The threaded walls of the plug and socket members are electrically connected by reason of the shell itself being of metal, and the contact elements 11 and 12 are also directly connected through the medium of a wire 14 engaged with the holding screw 15 of the element 12 and with a screw 16 that serves to secure a plate 17 to the insulator 10, this plate being electrically connected ment 11, as shown in Fig. 2.

As thus far described, it will-be evident that if the plug member is threaded into the usual electrical socket and a lamp or other instrument is in turn screwed into the socket member 9, electric current supplied to the ordinary socket memher will pass through this intermediate coupling and energize the lamp or other instrument. If, however, the lamp filament should be ruptured, the circuit will be broken.

with the contact ele- To maintain a circuit through the device I under the latter conditions, the followlng mechanism is preferably employed. Mounted on the insulator 10 and located within the hollow plug '7, is a thermostatic element 18 held in place by the screw 16, and thus electrically connected with the contact elements 11 and 12. This thern'iostati'c element comprises two metal leaves having ditferent coefficients of expansion, A corresponding thermostatic element 19. is mounted alongside the same on the insulating block 10 by i a fastener 20 and is provided with a contact screw 21. This contact screw is engaged by the thermostatic element 18 if the latter is warped and the screw will also engage said contact element 18 if the thermostatic element 19 carrying it is warped.

An electrical heating coil 22 surrounds the thermostatic element 18. One end thereof is electrically connected to the contact elements 11 and 12, as shown at 23 in Fig. 5, while the other end is electrically connected as illustrated at 24C toaresistance coil 25 surrounding the shell. This resistance is relatively high and much greater than that of the lamp or other electrical device mounted in the socket member 9. Another heating coil26 surrounds the other thermostatic element 19. One end of this coil is electrically connected directly to said thermostatic element, while the other end is connected to a resistance coil 28, as shown at 29. The coils 25 and 28 are located one within the other and are mounted on an insulator in the form of a spider 30 that surrounds and is carried by the socket member 9. Both coils have their outerterminals electrically connected to the shell 6, as shown at 81. The coil 28 is substantially of the same resistance as the lamp or other instrument that is electrically connected in the socket member 9.

Briefly described, the operation of the device is as follows: Tf a lamp is placed in the socket member 9, as long as this lamp is in operative condition, current will pass through the shell to the lamp and from the lamp directly back to the contact elements 11 and 12. While there is a closed shunt circuit across these two sets of contacts, in-

cluded in said circuit is the high resistance 25 which may be termed the master resistance, and through which little or no current will pass. If, however, the instrument becomes electrically inoperative, as for example, if the lamp filament is ruptured, then the current will pass through the shunt circuit, comprising the connection 23, the heating coil 22, the connection 24;, the resistance 25 and the connection 31. Consequently heat will be generated in the coil 22, and the thermostatic element 18 will be warped until it is brought into electrical contact with the screw 21. When this takes place, a second shunt circuit is closed, comprising the thermostatic element 18, the screw 21, the thermostatic element 19, the heating coil 26, the

connection 29, the resistance coil 28 and the connection 31. simply sufficient to compensate for the resistance that would ordinarily be occasioned by the lamp. This second shunt circuit there-f fore has very much less resistance than the first shunt circuit, so that the latter becomes practically inactive. The heater 26, however, causes the thermostatic element 19 to become bent so as to maintain the contact of the screw 21 with'the thermostatic element 18, and this latter shunt circuit is thus maintained. 1

In this structure, attention is called to the fact that as long as the lamp is operative, the mechanism by which the automatic shunt' The resistance coil 28 is circuit is established and maintained is inoperative and the parts are at rest. No material amount of current is therefore used in them. There is a relatively weak current flowing at all times while the lamp is lighted, through the high resistance, but it is insignificant and not enough to heat the thermal strip. If, however, the lamp should break or burn out, then there is an increase of current in this shunt which will heat the strip enough to warp it as described. When the shunt mechanism becomes inactive, the current utilized is practically the same as the lamp would require, so that the other members of the series operate as under normal conditions. In addition, it will be obvious that the device is exceedingly compact and relatively simple.

From the foregoing, it is thought that the construction, operation and, many advantages of the herein described invention will be apparent to those skilled in the art, without further description, and it will be understood that various changes in the size, shape, proportion and minor details of construction, may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention. 1

Having thus fully described my invention, what T-claim as new, and desire to secure by Letters Patent, is

1. In a device of the character set forth, the combination with leads for an instru ment to be normally operated, of a shunt circuit connecting the leads, a second shunt circuit for connecting the leads, including a normally open circuit closer, said circuit cated in the other circuit.

2. In a device of the character set forth,

the combination with leads for an electrical instrument to be normally operated, of a shunt circuit connecting the leads and including resistance, a second shunt circuit for connecting the leads and including circuit' controlling means, means in the first shunt circuit for operating the said circuit controlling means when current passes through said first shunt circuit by reason of the inoperativeness of an electrical instrument connected to the leads, and means in the second shunt circuit and operated by the current passing through aid second shunt circuit for continuing the operation of saidcircuit controlling means after its operation has been initiated by the first shunt circuit.

3., In a device of the character set forth, the combination with leads for an instrument to be normally operated, of a shunt circuit connecting the leads, a second shunt circuit for connecting the leads, including a normally open circuit closer, resistances in the different shunt circuits, said resistances respectively being of different values, said circuit closer comprising a pair of relatively movable thermostatic elements having portions movable into and out of contact, electrical heating means for one thermostatic element located in one circuit, and electrical heating means for the other thermostatic element located in the other circuit.

4|:- In a device of the character set forth, the combination with leads for an electrical instrument to be normally operated, of a normally closed shunt circuit connecting the leads and including resistance, a second shunt circuit for connecting the leads and including a normally open circuit control: ler, means in the first shunt circuit for closing said circuit controller when current passes through said first shunt circuit by reason of the inoperativeness of an electrical instrument connected to the leads, and means in the second shunt circuit operated by the current passing therethrough for maintaining the circuit controller closed after it has been closed by the means in the first shunt circuit.

5. In a device of the character set forth, the combination with leads for an instru ment to be normally operated, of a closed shunt circuit for connecting the leads and including resistance greater than that of the instrument to be operated; a second normally open shunt circuit for connecting the leads and including a normally open circuit closer having thermostatic means that is included in the first shunt circuit for closing the circuit closer when current is passed through the first circuit by reason of the failure of current to pass through an instrument connected to the leads.

6. In a device of the character set forth, the combination with leads for an instrument to be normally operated, of a closed shunt circuit connecting the leads and including resistance greater than that of the instrument to be operated, a second normally open shunt circuit connecting the leads and including a normally open circuit closer having thermostatic means included in both circuits for closing and holding closed the circuit closer when current is passed through said circuits" by reason of the failure of current to pass through an instrument connected to the leads.

7. In a device of the character set forth, the combination wlth leads for an instru- .ment to be normally operated, of a closed shunt circuit connecting the leads and including resistance greater than that of the instrument to be operated, a second normally open shunt circuit connecting the leads and including a normally open circuit closer, said circuit closer comprlsing a pair of relatively movable thermostatic elements for connecting the leads and including re-.

sistance that is approximately equal to that of the instrument to be operated, a normally open circuit closer in the second shunt circuit, means in the first shunt circuit for operating said circuit closer when an increased current is passed through said first shunt circuit, and means in the second shunt circuit operated by the current therein for maintaining the circuit closer closed.

9. In a device of the character set forth, the combination with a shell comprising a plug member and a socket member for detachably interfitting respectively with the socket and plug members of electrical apparatus, each of said members having setsof directly connected contact elements, the sets being normally electrically disconnected, and automatic electrically operated means for electrically connecting the sets when the same are electrically energized and the contact elements of the socket member are-electrically disconnected, and effecting their dis connection when the contact elements of the socket member are electrically connected, said means including movable elements housed within the plug member.

the combination with a current conducting shell having a hollow plug member formed 10. In a device of the character set forth, 7 i

at one end and a socket member formed at the other end electrically connected to the plug member by said shell, of a contact element inthe plug member insulated therefrom, and a contact element in the socket member insulated thereform, a'direct electrical connection between the contact elo= ments, and means within the plug for causing a shunt circuit connection between the shell and contact elements when the shell and contact elements of the socket member are electrically disconnected.

11. In a device of the character set forth, the combination with a current conducting continuous shell formed with a hollow externally threaded plug portion at one end and an internally threaded socket portion .at the other end,ot an insulator in the shell separating the plug and socket members, a contact element on one end of the plug insu lated therefrom, a contact element in the socket mounted on the insulator and eiec trically connected directly with the contact element of the plug, and means within the shell for creating a shunt circuit between the shell and contact elements when said shell and contact elements are electrically en'ergized and the shell and contact element of the socket are electrically disconnected.

12. In a device of the character set forth, the combination with a current conducting shell having a hollow plug member at one end and a socket member at'the other end electrically connected therewith, of a contact element on the plug member insulated therefrom and a contact element in the socket member insulated therefrom and electrically connected to the first mentioned contact element, an insulator mounted within the shell and separating the plug and socket members, said insulator constituting a support for the contact element of the socket member, a pair of thermostatic elements mounted on the insulator within the shell and relatively movable toward and from each other, said thermostatic elements having cooperating contact portions movable into and out of engagement with each other, a shunt circuit connection between the contact elements and the shell including a heater for one of the thermostatic elements and a resistance coil on the shell, and another shunt circuit between the contact ele- -ments and the shell including a heater for neraeea electrical connections between the lamp, the

thermostatic elements and the coils for causing the thermostatic elements to be placed in circuit to shunt the current when the lamp filament is ruptured.

15. The combination with an incandescent lamp, of a plug therefor for detachable engagement with the sockets arranged in series, said plug having master and compensating resistance coils associated therewith, thermostatic elements mounted within the plug and in circuit with the coils and means controlled by the thermostatic elements for shunting the current through the compensating coil when the lamp filament is ruptured.

16. The combination with an incandescent lamp, of a plug therefor, thermostatic elements mounted in the plug, an adjustable contact carried by one of the elements, master and compensating resistance coils carried by the plug, said thermostatic elements being in circuit with the coils, and means becoming operative when the lamp filament is ruptured to cause the current to be shunted to the thermostatic elements thereby causing said thermostatic elements to move toward each other until one element engages the other element.

In testimony whereof I aiiix my signature.

- WILL C. NEAHR. 

